The present invention relates to a plasma etching device. More specifically, the present invention relates to a plasma etching device that can freely control plasma density generated on the surface of a base, and/or a self bias potential on the surface of the base.
Recently, accompanying the increase in chip size of DRAM, MPU etc., there has also been a tendency to increase the diameter of a silicon substrate used as a substrate for these devices. In the field of semiconductor manufacture, etching of an oxide film or polysilicon etc. is one of the most important steps, but with a normal parallel RIE device that was used formerly it was not possible to achieve plasma performance (for example, process pressure of less than 50 mTorr, ion saturation current of at least 1 mA/cm2 (electron density of at least 1xc3x971010cmxe2x88x923)) required for fine pattern processing at less than 1.0 xcexcm. In order to solve this problem, a plasma source introduced into a magnetic field was developed, and as one example of a device containing this plasma source, a magnetron plasma etching device using a dipole ring magnet (hereinafter referred to as DRM) is well known (Japanese patent laid-open No. Hei 6-37054, FIG. 24 and FIG. 25),
However, with a magnetron plasma etching device using the above described DRM generation of low pressure high density plasma is possible, but it is very difficult to control plasma generated on the base with high precision. That is, by introducing a horizontal magnetic field onto the base, it is to be expected that making the plasma density uniform and making the self bias potential uniform on the base will be difficult. At the present time, a scheme for causing the magnetic field to have a slope (Japanese Patent Laid-open No. Sho. 62-21062) and causing the magnetic field introduced into a processing space to be rotated (Japanese Patent Laid-open No, 61-208223) have been adopted as methods of making the plasma density and self bias potential uniform. However, in the method of Japanese Patent Laid-open No. Sho. 62-21062, there was the problem that when the process pressure etc. varied, the optimal magnetic slope also varied. On the other hand, in the method of Japanese Patent Laid-open No, 61-208223, it was anticipated from outward appearances that plasma density would be made uniform for a base in a processing space, but a mechanism for causing rotation of the magnetic field was essential, and it was difficult to miniaturize the device.
The object of the present invention is to provide a plasma etching device capable of etching with respect to a base uniformly, and without charge up damage (generated as a result of potential deviation), independently of pressure and without causing rotation of magnetic field applying means, by making the density of plasma generated on a surface of the base uniform, and making a self bias potential uniform.
A first plasma etching device of the present invention is provided with two parallel plate type electrodes electrode I and electrode II, and means for applying high frequency power connected to the electrode I and electrode II, with a base to be subject to etching processing using plasma being mounted on a surface of the electrode I opposite to the electrode II, and further provided with means for applying a magnetic field being horizontal with respect to the surface of the base to be subjected to plasma etching, and being unidirectional. The plasma etching device further comprises an auxiliary electrode at least on an upstream side, with respect to the base, of a flow of electrons generated by the magnetic field applying means, and the auxiliary electrode includes a local electrode arranged on the side facing the electrode II and means for adjusting impedance provided at a part of the local electrode to be electrically connected with the electrode I.
A second plasma etching device of the present invention is provided with two parallel plate type electrodes electrode I and electrode II, and means for applying high frequency power connected to the electrode I and electrode II, with a base to be subject to etching processing using plasma being mounted on a surface of the electrode I opposite to the electrode II, and further provided with means for applying a magnetic field being horizontal with respect to the surface of the base to be subjected to plasma etching, and being unidirectional. The electrode II comprising a central portion electrically connected to ground, and an outer portion connected to a high frequency power supply capable of being controlled independently of a high frequency power supply connected to the electrode I.
A third plasma etching device of the present invention is provided with two parallel plate type electrodes electrode I and electrode II, and means for applying high frequency power connected to the electrode I and electrode II, with a base to be subject to etching processing using plasma being mounted on a surface of the electrode I opposite to the electrode II, and further provided with means for applying a magnetic field being horizontal with respect to the surface of the base to be subjected to plasma etching, and being unidirectional. The plasma etching device further comprises an auxiliary electrode at least on an upstream side, with respect to the base, of a flow of electrons generated by the magnetic field applying means, with the auxiliary electrode including a local electrode arranged on the side facing the electrode II and means for adjusting impedance provided at a part of the local electrode to be electrically connected with the electrode I, and the electrode II comprising a central portion electrically connected to ground, and an outer portion connected to a high frequency power supply capable of being controlled independently of a high frequency power supply connected to the electrode I.
A fourth plasma etching device of the present invention is provided with two parallel plate type electrodes electrode I and electrode II, and means for applying high frequency power connected to the electrode I and electrode II, with a base to be subject to etching processing using plasma being mounted on a surface of the electrode I opposite to the electrode II, and further provided with means for applying a magnetic field being horizontal with respect to the surface of the base to be subjected to plasma etching, and being unidirectional. An auxiliary electrode of a ring body is provided at a peripheral section of the base. The auxiliary electrode includes a local electrode arranged on the side facing the electrode II and means for adjusting impedance provided at a part of the local electrode to be electrically connected with the electrode I, and the impedance of the ring body at a section corresponding to an upstream side in an electron flow generated by the magnetic field applying means is lower than at other sections.
A fifth plasma etching device of the present invention is provided with two parallel plate type electrodes electrode I and electrode II, and means for applying high frequency power connected to the electrode I and electrode II, with a base to be subject to etching processing using plasma being mounted on a surface of the electrode I opposite to the electrode II, the electrode II comprising a central portion electrically connected to ground, and an ring body outer portion connected to a high frequency power supply capable of being controlled independently of a high frequency power supply connected to the electrode I, the impedance of the ring body at a section corresponding to an upstream side in an electron flow generated by the magnetic field applying means being lower than at other sections.
However, the impedance of the plasma etching device of the first, third and fourth inventions described above refers to the junction impedance between the auxiliary electrode and the electrode I.